This invention relates to a photoelectric conversion element and to a construction of a light-receiving surface that can be used for a photoconductive type image pick-up tube target or a solid state imager.
As a typical example of the photoelectric conversion element that can be used in a storage mode, there is a photoconductive type image pick-up tube such as shown in FIG. 1. The image pick-up tube consists of a light-transmitting substrate 1 called generally a "face plate", a transparent conductive film 2, a photoconductive layer 3, an electron gun and a jacket 5. An optical image formed on the surface of the photoconductive layer 3 through the face plate 1 is subjected to the photoelectric conversion, is stored as charge patterns on the surface of the photoconductive layer and is read by a scanning electron beam 6 in the time series arrangement.
Generally, a beam landing layer 7 is formed on the surface of the photoconductive layer 3 for the purpose of preventing the inversion and the injection of electrons from the scanning electron beam.
One of the significant characteristics required for the photoconductive layer 3 in this instance is that the charge patterns are not caused to decay by diffusion during the time interval in which specific picture elements are scanned by the scanning electron beam 6 (that is to say, during the storage time).
As an example of the prior art reference that propose to use an amorphous material consisting principally of silicon and containing hydrogen for the abovementioned photoconductive layer, mention can be made of "Appl. Phys. Lett.", 35(4), 15 Aug., 1979, p349-351.
A solid state imager using a photoconductor is disclosed, for example, by INTERNATIONAL ELECTRON DEVICES MEETING, December, 1979, p134-136. However, the photoconductor used in this prior art is Se-Ge-As chalcogenide glass but is not hydrogenated amorphous silicon that is to be employed as the photoconductor in the present invention.